Apparatus for the electric dissolution and precipitation of metals.



E. R. HOLDEN.

APPARATUS FOR THE ELECTRIC DISSOLUTIOIIIAND PRECIPITATION OF METALS.

APPLICATION FILED APR. I7. I911 Patented Feb. 25, 191$) 2 SHEETS-SHEET I.

E. R. HOLDEN. APPARATUS FOR THE ELECTRH] DISSOLUTION AND PRECIPITAHON 0F- METALS, APPLICATION FILED APR.17,I917. 9 5353239 Patentefi E60. 25, 1231".

2 SHEETSHSHEYET 2.

E. R .Hoiden EDWARD R. HOLDEN, OF LOS ANGELES, CALIFORNIA.

APPARATUS FOR THE ELECTRIC DISSOLUTION AND PRECIPITATION 0F METALS Specification of Letters Patent.

Patented Feb. 25, 1919.

Application filed April 17, 1917. Serial No. 162.689.

To all whom it may concern: 1

- Be it known that I, EnwAnn R. Home), a citizen of the United States, residing at Los Angeles, in the county of Los Angeles and State of California, have invented new and useful Improvements in Apparatus for the. Electric Dissolution and Precipitation of Metals, of which the following is aspecification.

This invention relates to an improved apparatus for el-ectro-chemically dissolving metals and their compounds from ores, and theprecipitation and recovery of the metals in a rapid, economical and etlicient manner.

The essence of this invention resides in the provision of means whereby a plurality of independent and distinct electric currents of different 'E. M. F. are distributed and dismetals. filed October 10th, 1916, Serial No;

121,902, which covers the process carried out by means of the apparatus claimed in the present application.

In the accompanying drawings, which form a part of thisspecification, I have illustrated a convenient and practical embodiment of my invention, and in which:

Figure l is a view in vertical section, partly in elevation, of an apparatus employed in carrying out my process, showing a part of the electrical device in diagram.

Fig. 2 is a diagrammatic view illustrating the electric circuits and the manner of distributing the electric current throughout an electrolyte.

Fig. 3 is a view in horizontal section on a reduced scale, as seen on the line 3-3, of Fig. 1.

Fig. t is .a detail in plan of the revolving resistance coil carriage and the wiper contact for delivering electric current thereto.

To carry out the action above referred to in the most advantageous manner, I preferably use a circular tank of any reasonable number of feet in diameter, and of a depth sufficient to hold large quantities of solu such as hard wood, hard rubber or other material. not affected by acid or alkaline solutions, nor electrolysis, together with a copper, mercury or other negative cathode on the bottom of the tank.

More specifically in the drawing, A indicates a tank of any suitable material, pref: erably wood, about six feet in diameter, and twelve feetv in depth, although other sizes may be found advantageous. In this tank a vertical shaft B of non-conducting material is mounted, and throughout its entire height at equal distances apart, carries a number of metallic paddles as anodes numbered from 1 to 9; anode 1 being placed just above a cathode C, comprising a copper or other metallic plate or mercury arranged to cover the bottom of the tank. -The paddles are here shown as comprising four blades to a set; each set constituting a separate anode. By repeated experiments I have found that in a tank twelve feet deep filled with a solution containing metals in solution, that the best electrolytic precipitation is obtained when the metallic anodes are set about twelve to fifteen inches apart; the lowest anode 1 being six to twelve inches, more or less, above the cathode C. The shaft is rotatedby gearing D or other suitable means.

On the upper part of the non-conducting shaft is a circular metallic contact ring E connected with a positive current of electricity, through a wiper contact F, connected with a conductor G, leading from one terminal of a source of electrical suppl or generator H; a conductor I leading rom the other terminal of the generator to the cathode C. On the lower end of the metallic contact ring E and attached thereto is a circular disk J of hard rubber or other nonconducting sulbstance. Resting upon and at tached to the disk J are separately wound individual resistance coils 1 to 9 as shown in Fig. 2, there being one resistance coil for each of the anodes attached to the shaft. The top of each resistance coil is connected with the contact ring E and the positive current of electricity passes from the contact ring into each resistance coil, the lower ends of which are resting on the disk J and-- each coil is connected with its own separate; insulated wire or conductor 1" to 9", lead ing down through the electrolyte to an anode. Each one of these separate resistance coils is so Wired as to convey a reguq v age as Will overcome the added resistance caused by the distance of each anode from the cathode. Each anode thus becomes an independent one, capable of disseminating the necessary amount of current density through the solution to overcome the resistance caused by the distance of each anode from the cathode whereby the electric current passing into the electrolyte is distributed throughout the whole solution in such a manner that the metals in solution are immediately and uniformly liberated into metallic ions from their compound condition and are precipitated on the cathode; the detailed operation of which is hereafter more fully explained.

At the bottom of the tank A a draw off pipe K, for the purpose of drawing off the mercury cathode or removing precipitates also serve as agitators for the solution, and

solution and for their preci itation and recovery and to increase the e ciency and potential condltions necessary in conducting electricity into a liquid, and for clearly exemplifying the improvement in the method of disseminating varying quantities of E. M. F. to separate anodes throughout the electrolyte, I herewith append the results of the. following tests conducted for the purpose of advanclng the art and to illustrate the improvements over those indicated inmy previous Letters Patent granted April 25th, 1916 numbered 1,181,077, and entitled Process of treating ores bearing precious metals.

I found by experiment in a tank three feet in diameter and nine feet in depth, containing a solution carrying gold and silver in solution, with sutficient sodium chlorid pres out to establish the necessary conductivity and a current of positive'electricity passing down through the electrolyte, by means of separate wires attached to a contact ring above, and connected with a number of anodes attached to a non-conducting shaft, but without using the resistance coils hereinbefore described, that the density of the current between the lowest anode 1 and the cathode was 690 times greater than the density of the current surrounding thehighest anode 9 at the top of the solution and that the several anodes from 2 to 9 inclusive indicated a constantly decreasing amount of amperes in proportion to their increased distance from the cathode and had therefore, only a trace or at best but a feeble dissolving and precipitating action on the metallic compounds in solution above the lowesta conducting shaft on which a number of anodes set in the same manner as above described were attached.

Each of the anodes, above the lowest one,

' which was in closest contact with the cathode,

showed a uniform proportional decrease in amperes, the density of the current between the lowest anode 1 and the cathode was 4.14 amperes per square foot of cathode surface, while the density of the current just below the top anode 9 was only .006 ampere per square foot of cathode surface.

The following table gives the registered ampere readings, indicated on a testing ammeter, per square foot of cathode surface, as registered by each anode separately, beginning with the lowest anode 1 and showing a decreased potential at each anode in proportion to the distance between each anode and the cathode:

Individual Distance Volts. anode from readings. cathode.

Amperes. Anode No. 9 12 .006 8' 6 Anode No. 8 12 .009 7 6 Anode No. 12 .014 6' 6 Anode No. 6 12 .026 5 6" Anode No.5... 12 .041 4 6 Anode No. 4.. 12 .060 3 6' Anode No. 3... 12 140 2' 6 Anode No. 2 12 .430 1 6" Anode No. 1 12 4.140 6" The following experiments are herew1th set forth for the purpose of comparison and to show the detailed operation of and advantages derived by the present process. So far as I am aware a current of electricity has never been disseminated and distributed throughout a solution by means of a plurality of anodes, through a conducting or non-conducting shaft, and therefore, I deem it necessary to set forth the operation in detail so that the improvement which I claim as new and useful can be fully understood by those desiring to take advantage of this process. I

An experiment was conducted in the above tank which contained 4,500 lbs. of 20% potassium cyanid solution, carrying gold and silver in solution. The solution also contained the necessary amount of sodium chlorid to establish the conductivity required.

The current was then led through the contact ring directly to each anode, passing thence through the electrolyte to the cathode for the purpose of precipitating the gold and silver out of the solution and'this operation continued for six hours. After each hour a sample of the solution was drawn through a pet cock in the side of the tank just below anodes 1. 5 and 9.

The solution obtained below anode 1 at the end of the first hour. showed that the gold and silver value of the solution had decreased 46% per ton of solution. The

sample taken simultaneously below anode 5 showed that the gold and silver value had decreased 36% per ton of solution, while the sample taken simultaneously below anode 9 had decreased only 6% per ton of solution. Samples taken at the end of the secondthird-fourthfifth and sixth hours, showed that the precipitation occurrred most rapidly during the first hour, but that the action continued proportionately the same during the remaining five hours at all the respective anodes.

The sample taken below anode 1 at the end of the sixth or final hour showed that the gold and silver value of the solution had decreased 98.2% per ton of solution, while the sample taken simultaneously below anode 5 showed the gold and silver value had decreased 75% per ton of solution, while the sample taken simultaneously below anode 9 had decreased only 50% per ton of solution. The entire contents of the tank was then withdrawn and the solution thoroughly mixed and showed a total precipitation of only 74.4 of the gold and silver.

thereby regulating the potential between each anode and the cathode, and producing throughout the solution, from the top to the bottom, the required amperage to establish the necessary potential simultaneously in all parts of the solution to deconn pose and precipitate the metals from their compounds, with the following result:

Individual Distance Volts.. anode om readings. cathode.

Amperes. Anode No. 9 12 2.50 8' 6" Anode No. 8... 12 2.36 7 6" Anode No 7 12 2.22 6 6" Anode No 6 12 2.08 5' 6" Anode No 5 12 1.94 4' 6" Anode No 4 12 1.83 3 6" Anode No 3 12 1.70 2' 6" Anode No 2. 12 1.62 1' 6 Anode No. 1 12 1.50 6

After the above regulated current had been disseminated throughout the electrolyte for one hour samples of the solution corresponding to those taken in test one were & V

drawn just below anode 1, 5 and 9. The solution taken below anode 1 had decreased in value in gold and silver 48% per ton of solution. The sample taken simultaneously just below anode 5 showed the gold and silver value of the solution had decreased 44% per ton of solution, while the sample taken at the same time, just below anode 9 had decreased 35% per ton of solution. Samples taken at the. end of. the secondthirdfourthfifth and sixth hours showed'that the precipitation was proportionately uniform at all the respective anodes. The samples taken at the end of the sixth or final hour showed that the gold and silver value of the solution had decreased below anode 1, 99.9% per ton of solution, while the sample taken simultaneously just below anode 5 showed the gold and silver value had de creased 99.7% per ton of solution, while the sample taken simultaneously just below anode 9 showed the gold and silver value had decreased 99.5% per ton of solution.

A continuation of the operation of the current through the electrolyte for a longer period would have precipitated the trace of gold and silver remaining in the solution, but the time required and the current costs in recovering same, commercially precluded carrying the operation further.

The second table above referred to shows a regulated decrease of amperage from the bottom to the top. The applicant does not desire, however, to limit himself to the method of regulating the amperage so that the highest amperage is at the bottom and the lowest at the top, as indicated by this table, but may regulate the amperage that the values of the table may be reversed, and the highest amperage will be at the top and the lowest at the bottom, or the amperage may be substantially equal at each anode. The preferred method is to have the highest amperage at the top, decreasing toward the bottom, but my method broadly contemplates regulation of the amperage at different anodes in the solution.

The use of a non-conducting shaft or one entirely constructed of non-conducting material and carrying no current into the electrolyte, makes possible the dissemination of different E. M. F. through various anodes at different points in the solution, with the result above described.

The above described method of distributing and disseminating an electric current, is also adaptable to and greatly accelerates the dissolution of metals and their compounds from ores in (for example) a cyanid electrolyte by the.liberation of cyanogen, at

the cathode, according to the following well known equations:

2K+Cl (K at cathode) 2CN+2K=KCN thereby regenerating the solvent solution and maintaining comparatively uniform and constant strength therein, throughout the operation, which results in bringing about a very much more rapid and efficient dissolution of the metals and their compounds than can be obtained if the electric current is not distributed and disseminated by means of a plurality of anodes throughout the electrolyte.

Similar regeneration of solvent is brought about when bromin, chlorin, sulfate or other solvent is used.

I am aware of the fact that patents have been issued in this and other countries for .the use of a current of electricity in an electrolyte containing metals for the purpose of dissolution or precipitation, or both, and 1 do not claim anything by reason of any such,

cal tank, a vertical non-conducting shaft mounted therein, means for rotating said shaft, a plurality of agitator arms fast to said shaft and arranged in sets one above the other, a cathode at the bottom of said tank, a plurality of independent electric conductors leading to said sets of agitator arms, there being one conductor for each set, said arms constituting anodes, and means for independently controlling the E. M. F. of the current delivered to each set of anodes.

2. An apparatus for treating solutions containing metals, comprising a tank, a Vertical shaft mounted therein, means for rotating said shaft, a cathode, a plurality of agitator arms fast to said shaft and arranged at various distances from said cathode, a plurality of independent conductors leading to said agitator arms, said arms constituting anodes, and means for independently controlling the E. M. F. of the current delivered to each anode.

In testimony whereof I have signed my name to this specification.

EDWARD R. HOLDEN. 

